Literacy and blood pressure--do healthcare systems influence this relationship? A cross-sectional study.
BACKGROUND
Limited literacy is common among patients with chronic conditions and is associated with poor health outcomes. We sought to determine the association between literacy and blood pressure in primary care patients with hypertension and to determine if this relationship was consistent across distinct systems of healthcare delivery.


METHODS
We conducted a cross-sectional study of 1224 patients with hypertension utilizing baseline data from two separate, but similar randomized controlled trials. Patients were enrolled from primary care clinics in the Veterans Affairs healthcare system (VAHS) and a university healthcare system (UHS) in Durham, North Carolina. We compared the association between literacy and the primary outcome systolic blood pressure (SBP) and secondary outcomes of diastolic blood pressure (DBP) and blood pressure (BP) control across the two different healthcare systems.


RESULTS
Patients who read below a 9th grade level comprised 38.4% of patients in the VAHS and 27.5% of the patients in the UHS. There was a significant interaction between literacy and healthcare system for SBP. In adjusted analyses, SBP for patients with limited literacy was 1.2 mmHg lower than patients with adequate literacy in the VAHS (95% CI, -4.8 to 2.3), but 6.1 mmHg higher than patients with adequate literacy in the UHS (95% CI, 2.1 to 10.1); (p = 0.003 for test of interaction). This literacy by healthcare system interaction was not statistically significant for DBP or BP control.


CONCLUSIONS
The relationship between patient literacy and systolic blood pressure varied significantly across different models of healthcare delivery. The attributes of the healthcare delivery system may influence the relationship between literacy and health outcomes.
Powers
Benjamin J
BJ
Center for Health Services Research in Primary Care, Durham VAMC, Durham NC, USA. power017@mc.duke.edu
Olsen
Maren K
MK
Oddone
Eugene Z
EZ
Thorpe
Carolyn T
CT
Bosworth
Hayden B
HB
D000046:Academic Medical Centers; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D004522:Educational Status; D005260:Female; D054624:Health Status Disparities; D006801:Humans; D006973:Hypertension / Q000150:complications*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009657:North Carolina; D016032:Randomized Controlled Trials as Topic; D014481:United States; D014493:United States Department of Veterans Affairs; D055815:Young Adult